This invention relates generally to raising and lowering columns, ie columns which comprise a relatively fixed base part and an upper part which can be raised and lowered relative to the base part. More particularly, the invention concerns apparatus for raising and lowering the columns, and a method of attaching the apparatus to the columns.
Operation of raising and lowering columns is generally performed by one or more piston and cylinder devices which is/are secured to respective attachment points on the two column parts. In locations where a large number of such columns are fitted, it is expensive to provide each column with its own individual piston and cylinder device(s). Instead, a so called counterbalance unit is employed, which is moved from column to column and on which the piston and cylinder device(s) are mounted for detachable securement to whichever column needs to be serviced/repaired. Such securement is often performed by manual lifting of the piston and cylinder device(s) into position on the column. This can be a hazardous operation, particularly where tall columns are concerned and the piston and cylinder device(s) are large and therefore heavy.
DE-A-1901659 discloses one example of such a counterbalance unit, wherein the piston and cylinder device is carried on a wheeled support. Although the support does assist in the maneuvering of the piston and cylinder into position, there is still a danger that the device will fall during the process of its attachment to the column, with a resultant risk of injury to the operative or operatives.